Maybe Tito has enough money invested and in the bank he doesnt need Don's money. Tito shows he is the bigger man and forgives Don King and now can move on with his life and put this in the past, where it belongs

Ali let King slide off with a few million for similar reasons. DK sent a mutual friend to Ali with a briefcase full of cash, but to receive it, he had to forgive the missing money and Ali accepted.

Lawsuits take years going through the system, where lwayers have to be paid up front for years of work. For fighters who already have enough money, they'll just let the miserable snake have the money instead of taking it to the courts.